1. Technical Field
The present disclosure relates to a connection between a seat and a bicycle frame. More particularly, the present disclosure relates to a seat post.
2. Description of Related Art
A seat post is a tube for fixing a seat on a bicycle. More specifically, the seat post is telescopic for changing the height of the seat to fit users. Furthermore, the seat post can use threads, clamp, or pneumatic cylinder to fix the height of the seat.
As to the pneumatic cylinder, the seat post has a control lever for actuating the pneumatic cylinder. The seat post will be extended when the pneumatic cylinder is actuated and the user does not sit on the seat yet. The seat post will be contracted when the pneumatic cylinder is actuated and the user is sitting on the seat. The height of the seat is fixed when the pneumatic cylinder is shut down. Obviously, the adjusting speed of the pneumatic cylinder is better than threads and clamp.
However, the drawback of the pneumatic cylinder is that the pneumatic cylinder is easily to be compressed when the pneumatic cylinder is shut down and under a force. In other words, the height of the seat is changed when the user is sitting on the seat and compresses the pneumatic cylinder, even if the height of the seat is fixed. Therefore, some strength of the user for pedaling will transmit to the pneumatic cylinder and compress the pneumatic cylinder. It wastes the work of the user for pedaling. As above, it is difficult to increase the fixing stiffness of the seat post.